The structure of behavioral variation within a genotype

Individual animals vary in their behaviors. This is true even when they share the same genotype and were reared in the same environment. Clusters of covarying behaviors constitute behavioral syndromes, and an individual’s position along such axes of covariation is a representation of their personality. Despite these conceptual frameworks, the structure of behavioral covariation within a genotype is essentially uncharacterized and its mechanistic origins unknown. Passing hundreds of inbred Drosophila individuals through an experimental pipeline that captured hundreds of behavioral measures, we found sparse but significant correlations among small sets of behaviors. Thus, the space of behavioral variation has many independent dimensions. Manipulating the physiology of the brain, and specific neural populations, altered specific correlations. We also observed that variation in gene expression can predict an individual’s position on some behavioral axes. This work represents the first steps in understanding the biological mechanisms determining the structure of behavioral variation within a genotype.

Negative Symptoms and Behavioral Alterations Associated with Dorsolateral Prefrontal Syndrome in Patients with Schizophrenia

The present study had three main aims: (1) to explore the possible relationships between the two dimensions of negative symptoms (NS) with the three frontal behavioral syndromes (dorsolateral, orbitofrontal and the anterior or mesial cingulate circuit) in patients with schizophrenia; (2) to determine the influence of sociodemographic and clinical variables on the severity of the two dimensions of NS (expressive deficits and disordered relationships/avolition); and (3) to explore the possible relationships between the two dimensions of NS and social functioning. We evaluated a group of 33 patients with schizophrenia with a predominance of NS using the self-reported version of the Frontal System Behavior scale. To quantify the severity of NS, the Assessment of Negative Symptoms (SANS) scale was used. The results revealed that the two dimensions of NS correlate positively with the behavioral syndrome of dorsolateral prefrontal origin. Regarding the influence of sociodemographic and clinical variables, in patients with a long evolution the NS of the expressive deficits dimension were less severe than in patients with a short evolution. A negative correlation was found between the severity of NS of the disordered relationships/avolition dimension and perceived social functioning. Our results show the importance of differentiating between the two dimensions of NS to characterize better their possible frontal etiology and impact on clinical course and social functioning.

The role of trade-offs and feedbacks in shaping integrated plasticity, behavioral syndromes, and behavioral correlations

Despite a decade and a half of intensive research effort, we still have little understanding of why behavioral responses are frequently correlated. This gap in our understanding stems from the fact that much of the work looking into behavioral correlations has focused on among-individual correlations, i.e. "behavioral syndromes". Unfortunately, this focus on syndromes ignores the fact that behavioral correlations are, instead, primarily due to within-individual correlations

African forest elephant movements depend on time scale and individual behavior

The critically endangered African forest elephant (Loxodonta cyclotis) plays a vital role in maintaining the structure and composition of Afrotropical forests, but basic information is lacking regarding the drivers of elephant movement and behavior at landscape scales. We use GPS location data from 96 individuals throughout Gabon to determine how five movement behaviors vary at different scales, how they are influenced by anthropogenic and environmental covariates, and to assess evidence for behavioral syndromes—elephants which share suites of similar movement traits. Elephants show some evidence of behavioral syndromes along an ‘idler’ to ‘explorer’ axis—individuals that move more have larger home ranges and engage in more ‘exploratory’ movements. However, within these groups, forest elephants express remarkable inter-individual variation in movement behaviours. This variation highlights that no two elephants are the same and creates challenges for practitioners aiming to design conservation initiatives.

Species comparison of among- and within-individual variation and correlations

Individuals frequently differ consistently from one another in their average behaviors (i.e. “animal personality”) and in correlated suites of consistent behavioral responses (i.e. “behavioral syndromes”). However, understanding the evolutionary basis of this (co)variation has lagged behind demonstrations of its presence. This lag partially stems from comparative methods rarely being used in the field. Consequently, much of the research on animal personality has relied on “adaptive stories” focused on single species and populations. Here we used a comparative approach to examine the role of phylogeny in shaping patterns of average behaviors, behavioral variation, and behavioral correlations. In comparing the behaviors and behavioral variation for five species of Gryllid crickets we found that phylogeny shaped average behaviors and behavioral (co)variation. Variation in average exploratory behavior and response to cues of predator presence attributable to phylogeny was greater or comparable to the magnitude of “personality variation”. Likewise, magnitudes of variation were concordant with evolutionary relationships and behavioral correlations were consistent across species. These results suggest that phylogenetic constraints play an important role in the expression of animal personalities and behavioral syndromes and emphasize the importance of examining evolutionary explanations within a comparative framework.

Sex-specific behavioral syndromes allow the independent evolution of behavioral dimorphism

When selection differs by sex, the capacity for sexes to reach optimal phenotypes can be constrained by the shared genome of males and females. Because phenotypic traits are often correlated, this difference extends across multiple traits and underlying genetic correlations can further constrain evolutionary responses. Behaviors are frequently correlated as behavioral syndromes, and these correlations often have a genetic basis. However, whether cross-sex and across behavior correlations lead constrained evolution remains unknown. Here, we show that a boldness-activity syndrome is strongly sex-specific at the genetic level in the western field cricket (Gryllus integer) and that emergence from a shelter is genetically independent between males and females. However, male activity is strongly related to female shelter emergence, creating the potential for biased responses to selection. Our results show that the sex-specific genetic architecture of behavioral syndromes can shape the evolution of behavioral phenotypes.

Do Females in a Unisexual-Bisexual Species Complex Differ in Their Behavioral Syndromes and Cortisol Production?

Studies of suites of correlated behavioral traits (i.e., behavioral syndromes) aid in understanding the adaptive importance of behavioral evolution. Behavioral syndromes may be evolutionarily constrained, preventing behaviors from evolving independently, or they may be an adaptive result of selection on the correlation itself. We tested these hypotheses by characterizing the behavioral syndromes in two sympatric, closely related species and testing for differences between the species. We studied the unisexual Amazon molly (Poecilia formosa) and one of its bisexual, parent species, the sailfin molly (P. latipinna). Sympatric female sailfin and Amazon mollies compete for mating which could affect the behavioral syndromes found in each species. We identified a behavioral syndrome between exploration and activity in both species that did not differ between species. Additionally, we explored the relationship between a stress response hormone, cortisol, and behavioral type, and did not detect a relationship. However, P. formosa differed from P. latipinna in their cortisol release rates. Behavioral syndromes may be constrained in this complex, aiding in mate acquisition for P. formosa by virtue of having a similar behavioral type to P. latipinna. The difference between the females in cortisol release rates may be a useful mate identification cue for males to offset higher mating mistakes associated with the similar behavioral types.